1. Field of the Invention
The invention relates to electrically energized linear motors or solenoids.
2. Description of the Prior Art
Bistable solenoids having an armature which can be actuated to either of two stable positions as a function of the polarity of a D.C. voltage applied to the coil of the device are well known. Such devices commonly include an armature or plunger which is latched in an actuated position by residual magnetism in a magnetic circuit after the coil is deenergized, and considerable electrical energy is required to move the armature or plunger from its latched position. Because of the residual magnetism in bistable solenoid constructions affecting the armature, such constructions are not suitable for positioning devices wherein the armature must be selectively positionable within a defined range of operation.
A linear motor with a movable coil, which serves to selectively position an output member in response to an input control signal, is disclosed in U.S. Pat. No. 3,984,745 of The Singer Company. However, it is a disadvantage of this type of construction that movable wire leads are required for the coil. Furthermore, movable coils are difficult to properly construct for their intended purpose.